A few tips to try if you're having problems getting SEP2 to run properly - based on months as a beta tester and reading about assorted problems.

1. SEP2 is an "early adopter" in using your graphic card's graphic processing unit (GPU). Not all cards work! The problems usually show up in the form image quality problems - odd colors, square patches with different tonality than the rest of the image, etc. The solution is to open SEP2's Settings menu and disable the GPU. You must restart SEP2 after doing this for it to take effect.

2. Odd crashes and startup difficulties. This next tip isn't a cure all but may solve your particular problem. The Nik Selective Tool (the little window that pops up over your host program, CS, LR,...) is known to occasionally cause problems - usually as a result of installing a new plug-in - key work here is install. Apparently install order among other things can matter and cause things to go south - hopefully Nik eventually fixes their install routines to guard aginst this & to clean up after themselves BUT in the meantime - if you have Viveza 2 or Color Efex Pro 3 installed - reinstall one or both and see if that fixes the problem (reinstalling CEP3 fixed it for me several times during beta as several fresh SEP2 installs messed it up again). Can't hurt and takes just a minute or two.

3. When all else fails - or maybe even before trying anything else - the generic "fix-it" for many SEP2 problems during beta for many, many testers was simply to reinstall SEP2. I don't know, but suspect, that once you move to the top of the Nik support queue this is going to be the first thing that they suggest.

Hope this helps. Tip #1 was the solution to Photojazz's recent thread problem.